A Solid State Transformer Based on a Single-Stage Three-Phase AC-DC T-Type Converters

Conventional power transformers are equipment that are used to raise or lower voltages and currents and transfer energy in transmission and distribution systems. They are established and widely accepted devices, however, these transformers have limitations, as they do not have an onboard control system capable of controlling voltages and currents, an increase in reactive power and propagation of harmonics to the electrical network can occur. Therefore, the development of new technologies that can perform voltage and current transformation without presenting such deficiencies is necessary, and one of these technologies is the solid-state transformer (SST). Thus, this paper proposes a three-phase and bidirectional AC-DC converter, with an active power of 50 kW, voltages of 7.2 kVac and 800 Vdc, for applications in SSTs. The proposed topology is based on Dual Active Bridge (DAB) converters applied to the secondary and primary sides, respectively. In the course of this paper, it is also proposed to use the 15 kV/20 A silicon carbide (Sic) insulated gate bipolar transistor (IGBT) for the primary side with a diode in antiparallel to the IGBT of the 10 kV/10 A junction barrier schottky (JBS) type.